Suguru Kimoto

Sex differences in denture satisfaction.

OBJECTIVES Males and females differ in their responses to many health conditions and treatments. The aim of this randomized clinical trial was to determine whether there are differences in the way that male and female edentulous elders rate their satisfaction with new mandibular implant overdentures (IODs) and conventional dentures (CDs), at 6 and 12 months following delivery. METHODS Edentulous elders (n=256) were randomly assigned to receive maxillary conventional dentures and either mandibular overdentures supported by two implants with ball attachments or conventional dentures. Participants rated their general satisfaction, as well as other features of their dentures (comfort, stability, ability to chew, aesthetics, etc.) prior to treatment and 6 and 12 months after delivery. RESULTS Ratings of satisfaction with IODs were significantly higher than with CDs. Six months after delivery, females in the CD group rated their general satisfaction and satisfaction with ability to chew and aesthetics significantly lower than did the males. The sex differences in the CD group remained at 12 months after delivery. However, males and females in the IOD group rated their general satisfaction and all six subcategories equally. CONCLUSIONS Elderly females are less satisfied with conventional dentures than elderly males with regards to aesthetics and ability to chew, but equally satisfied with implant overdentures. At 6 and 12 months after delivery, elderly edentulous males and females wearing mandibular implant overdentures were significantly more satisfied than those wearing conventional dentures.

Efficacy and Safety of an Intraoral Electrostimulation Device for Xerostomia Relief: A Multicenter, Randomized Trial

OBJECTIVE To evaluate the efficacy and safety of an intraoral electrostimulation device, consisting of stimulating electrodes, an electronic circuit, and a power source, in treating xerostomia. The device delivers electrostimulation through the oral mucosa to the lingual nerve in order to enhance the salivary reflex. METHODS The device was tested on a sample of patients with xerostomia due to Sjögrens syndrome and other sicca conditions in a 2-stage prospective, randomized, multicenter trial. Stage I was a double-blind, crossover stage designed to compare the effects of the electrically active device with the sham device, each used for 1 month, and stage II was a 3-month open-label stage designed to assess the long-term effects of the active device. Improvement in xerostomia severity from baseline was the primary outcome measure. RESULTS A total of 114 patients were randomized. In stage I, the active device performed better than the sham device for patient-reported xerostomia severity (P<0.002), xerostomia frequency (P<0.05), quality of life impairment (P<0.01), and swallowing difficulty (P<0.02). At the end of stage II, statistically significant improvements were verified for patient-reported xerostomia severity (P<0.0001), xerostomia frequency (P<0.0001), oral discomfort (P<0.001), speech difficulty (P<0.02), sleeping difficulty (P<0.001), and resting salivary flow rate (P<0.01). CONCLUSION Our findings indicate that daily use of the device alleviated oral dryness, discomfort, and some complications of xerostomia, such as speech and sleeping difficulties, and increased salivary output. The results show a cumulative positive effect of the device over the period of the study, from baseline to the end of the trial.

Distortion Behavior of Heat-activated Acrylic Denture-base Resin in Conventional and Long, Low-temperature Processing Methods

There have been many reports on fatal distortion of heat-activated acrylic denture-base resin which is still widely used in the field of removable prosthodontics. However, these reports have failed to report quantitatively on polymerization and thermal shrinkage factors. In the present study, we attempted to verify that the shrinkage of heat-activated acrylic denture-base resin was caused mainly by thermal contraction after processing. Furthermore, we examined the degree of distortion resulting from long, low-temperature processing, and compared the results with that of the conventional method. The strain gauge and thermocouple were embedded in a specimen at the time of resin packing. The measurement started from the beginning of processing and continued until the specimen was bench-cooled and immediately before and after it was de-flasked, as well as during seven-day immersion in water at 37°C. The resin expanded when processed by the conventional method. Meanwhile, mild shrinkage, possibly polymerization shrinkage, was observed when the resin was processed by the low-temperature method. This suggested that polymerization shrinkage was compensated for by thermal expansion during processing by the conventional method. Moreover, the shrinkage strains in the period from the completion of processing to immediately after de-flasking, in both the conventional and low-temperature methods, were identical to the theoretical value of thermal shrinkage which we obtained by multiplying the linear coefficients of thermal expansion by temperature differences. The shrinkage strain in the specimen processed by the low-temperature method, measured from the end of processing to immediately after de-flasking, averaged 64% of that in the specimen processed by the conventional method. The results revealed quantitatively that the shrinkage of heat-activated acrylic denture-base resin was mainly thermal shrinkage, and demonstrated the advantage of the low-temperature method in reducing thermal shrinkage.

Intraoral electrostimulator for xerostomia relief: a long-term, multicenter, open-label, uncontrolled, clinical trial

OBJECTIVE A previous sham-controlled multinational study demonstrated the short-term efficacy and safety for xerostomia treatment of an intraoral device that delivers electrostimulation to the lingual nerve. The objective of this study was to test the hypothesis that those beneficial effects would be sustained over an 11-month period. STUDY DESIGN The device was tested on a mixed sample of 94 patients with xerostomia in an open-label, uncontrolled, prospective multicenter trial. Statutory outcome assessments were done at 5th, 8th, and 11th months and analyzed by multiple comparisons. RESULTS Improvements achieved at month 5 from baseline were sustained throughout the follow-up period for the primary outcome, xerostomia severity, and the secondary outcomes resting whole salivary flow rate, xerostomia frequency, oral discomfort, and difficulties in speech, swallowing, and sleeping. No significant side effects were detected. CONCLUSIONS The beneficial effects of a removable intraoral electrostimulating device were sustained for an 11-month period.

Rotational movements of mandibular two-implant overdentures

OBJECTIVES Clinicians have reported that their patients complain that their mandibular two-implant overdentures (IOD) rotate. Therefore, we studied the frequency and severity of rotation of IODs with two-ball attachments, how rotation may influence perceived satisfaction ratings of chewing ability, and the factors that are involved in the rotation of IODs. MATERIAL AND METHODS Seventy-nine participants were recruited and asked to rate their general satisfaction of their IODs, as well as their ability to chew foods, the existence of any mandibular denture rotation, and to what degree denture rotation bothered them. Data on participant sociodemographic, anatomical, and prosthesis characteristics were also collected. Students t-test and logistic regression analyses were performed to analyze the differences between participants who did (R group) and did not report (NR group) denture rotation. RESULTS Thirty-seven of 79 participants were aware of rotational movement in their IODs. These patients were significantly less satisfied with their chewing ability than those who felt no rotation (69.1 mm R group vs. 82.9 mm), and discomfort caused by the rotation bothered them moderately (39/100 mm). The multivariate logistic regression analysis revealed that the arrangement of the anterior teeth and the length of the denture are significantly associated with awareness of denture rotation. Thirty-eight percent in the R group and 31% in the NR group had non-scheduled visits. CONCLUSIONS Rotational movement with a mandibular two-IOD has a negative effect on perceived chewing ability and is associated with anterior tooth arrangement and denture length.

Evaluation of adhesive properties of three resilient denture liners by the modified peel test method.

The characteristics of adhesive properties between a denture base and resilient denture liner were investigated by a modified peel test with an L-shaped metal attachment. Three commercially resilient denture lining materials, namely GC Reline Soft (S), GC Reline Extra Soft (ES), and GC Reline Ultra Soft (US), were evaluated. Acrylic resin (GC Acron) was used as denture base material. Peel specimens consisting of the denture base acrylic resin and resilient denture liner were tested after storage for 1 and 30 days in distilled water at 37 degrees C. The modified peel test method gave load-displacement curves and work of adhesion (W(A)) values of the denture base material and resilient denture liner. The W(A) of specimens after 1 day of storage ranged from 1.71 to 2.55 N mm(-1) and increased in the order from US to S to ES. On the other hand, the W(A) of specimens after 30 day of storage ranged from 1.44 to 2.47 N mm(-1) and increased in the order from US to ES to S. US had significantly lower W(A) after 1 and 30 days of storage than did S and ES (P<0.05). Comparison of the W(A) between 1 and 30 days, reveals large differences for ES and US, but not for S. This could be explained by the difference in failure modes. Within the limitations of this investigation, it was concluded the modified peel test is effective for evaluating the adhesion between denture base material and a resilient denture liner.

Randomized controlled trial to investigate how acrylic-based resilient liner affects on masticatory ability of complete denture wearers

The aim of this study was to determine the effects of an acrylic-based resilient liner (ARL) on masticatory ability by verifying the null hypothesis that masticatory performance and mandibular movements do not differ between people who wear mandibular complete dentures with ARL and those who wear complete dentures with conventional acrylic resin (CAR). From April 2004 to July 2006, we conducted a randomized controlled trial study at two centres. After written informed consent was obtained from 74 edentulous patients, they were randomly allocated to either the ARL group or CAR group. Masticatory performance and mandibular movement at the lower incisal point during chewing were measured as the outcomes. We did not observe significant differences in both outcomes between the groups. The chewing cycles were significantly different during the initial, middle, and final phases of mastication. Within the limitations of the current study, the results indicate that the acrylic-based resilient denture liners used have no clinical impact on the masticatory ability of complete denture wearers.

Investigation on how renewal of complete dentures impact on dietary and nutrient adequacy in edentulous patients

PURPOSE The aim of this study is to investigate changes of diet and nutrient adequacy between complete denture wearers with their existing dentures and those with new dentures. METHODS After obtained their written informed consent 30 patients who visited Nihon University School of Dentistry at Matsudo Affiliated Hospital from March 2004 to November 2005 were asked to record their 3 consecutive days meals and to take a picture of them. Furthermore, foods which they can eat with their dentures were examined the questionnaire developed by Hirai. Referring to the obtained records and pictures, one dietitian interviewed to confirm the exact intakes of meals. In addition, the masticatory ability was calculated using the questionnaire. The nutrient adequacy and masticatory score determined at the time of the first and second survey were examined by repeated-measures ANOVA. A p-value less than 0.05 was considered statistically significant. RESULT The total intake of energy and nutrients was almost over 100% in both the groups. However, no statistically significant difference was obtained. The masticatory score with the existing and new denture were 66.1+/-18.5 and 58.3+/-19.9, respectively. The score increased significantly in the new denture group when compared with that of the existing denture group. CONCLUSION The self-evaluation of the masticatory function improved after the switch from the old to new dentures.

Pilot study to assess the potential of oral myofunctional therapy for improving respiration during sleep

PURPOSE The present study was designed to assess the potential of oral myofunctional therapy (OMFT) for improving respiration parameters, Apnea-Hypopnea Index (AHI), and saturation of peripheral oxygen (SpO2) during sleep. METHODS The Epworth Sleepiness Scale (ESS) was administered to 92 students in class time at the Nihon University School of Dentistry at Matsudo. The results showed that 15 students had a high ESS. Of the 15 students who had learnt about their excessive sleepiness, six students expressed their intention to receive treatment for their sleep condition. They volunteered as subjects for the study. The Lip Trainer Patakara(®) was used for labial closure force (LCF) training for 2 months. LCF, AHI and SPO2 during sleep were measured before training and after 2 months training. The paired t-test was applied for statistical analyses. RESULT LCFs before and 2 months after training were 8.8 ± 1.6 and 12.9 ± 0.6N, respectively. LCF significantly increased after training compared to that before training. SpO2 before training and after training were 90.0 ± 2.9% and 96.8±0.8%, respectively. SpO2 after training was significantly increased compared to that before training. AHI before and after training were 15.1 ± 3.4 and 9.2 ± 1.5 events/h, respectively. AHI after training was significantly decreased compared to that before training. CONCLUSION From this study, the following conclusions were made: (1) OMFT significantly increases LCF; and (2) the AHI and SpO2 during sleep are significantly improved after OMFT.

Survival analysis of mandibular complete dentures with acrylic-based resilient liners.

OBJECTIVE The purpose of this long-term randomised controlled trial was to compare the longevity of dentures constructed using a conventional acrylic resin (CAR) to that of dentures constructed using an acrylic-based resilient liner (ARL). MATERIALS AND METHODS The follow-up study was essentially carried out by annual telephone calls to each of the 67 participants. The Kaplan-Meier method and life-table analysis were used for univariate analyses. The Cox proportional-hazards test was used as a final model for statistically adjusting predictor variables such as sex, clinician type, mandibular denture type and age at denture delivery. RESULTS The denture type was likely to affect the survival time of the dentures, while the sex and clinician type were not. The group using acrylic-based resilient denture liners had twice the risk of having shorter denture-survival times than those using conventional acrylic resin dentures. Younger participants were likely to have a reduced risk of having shorter denture-survival times than older participants. CONCLUSION We conclude that mandibular complete dentures constructed using ARL are twice as likely as dentures constructed using CAR to have shorter denture survival times, mainly because of material deterioration.